β-D-glucuronidase activity triggered monitoring of fecal contamination using microbial and chemical source tracking markers at drinking water intakes

ABSTRACT: ntense rainfall and snowmelt events may affect the safety of drinking water, as large quantities of fecal material can be discharged from storm or sewage overflows or washed from the catchment into drinking water sources. This study used β-D-glucuronidase activity (GLUC) with microbial source tracking (MST) markers: human, bovine, porcine mitochondrial DNA markers (mtDNA) and human-associated Bacteroidales HF183 and chemical source tracking (CST) markers including caffeine, carbamazepine, theophylline and acetaminophen, pathogens (Giardia, Cryptosporidium, adenovirus, rotavirus and enterovirus), water quality indicators (Escherichia coli, turbidity) and hydrometeorological data (flowrate, precipitation) to assess the vulnerability of 3 drinking water intakes (DWIs) and identify sources of fecal contamination. Water samples were collected under baseline, snow and rain events conditions in urban and agricultural catchments (Québec, Canada). Dynamics of E. coli, HF183 and WWMPs were similar during contamination events, and concentrations generally varied over 1 order of magnitude during each event. Elevated human-associated marker levels during events demonstrated that urban DWIs were impacted by recent contamination from an upstream municipal water resource recovery facility (WRRF). In the agricultural catchment, mixed fecal pollution was observed with the occurrences and increases of enteric viruses, human bovine and porcine mtDNA during peak contaminating events. Bovine mtDNA qPCR concentrations were indicative of runoff of cattle-derived fecal pollutants to the DWI from diffuse sources following rain events. This study demonstrated that the suitability of a given MST or CST indicator depend on river and catchment characteristics. The sampling strategy using continuous online GLUC activity coupled with MST and CST markers analysis was a more reliable source indicator than turbidity to identify peak events at drinking water intakes

Priorisation des sources de contamination fécale en milieu urbain : pertinence de l’utilisation de marqueurs moléculaires et chimiques comme traceurs de rejets d’eaux usées

«RÉSUMÉ: Une gestion efficace des épisodes de contamination fécale des systèmes aquatiques nécessite dans un premier temps une identification des sources de contamination avant de pouvoir mettre en place des pratiques de gestion et de restauration de la qualité d’un système. Les indicateurs bactériens classiques (E. coli, coliformes fécaux) utilisés dans le suivi de la qualité des eaux bien qu’ils indiquent la présence d’une charge fécale récente ne permettant pas une différenciation de l’origine de la pollution fécale. Un travail important a été réalisé ces dernières années afin de développer une nouvelle approche, dénommée le suivi de sources microbiennes (SSM) ou Microbial Source Tracking (MST). Les techniques de suivi des sources microbiennes sont destinées à permettre aux praticiens et aux chercheurs d'identifier la ou les sources de pollution fécale dans les eaux. Plusieurs recherches ont permis d’identifier des marqueurs microbiologiques et chimiques susceptibles de discriminer les différentes sources, cependant, il n'existe pas de méthodes « standard » définies pour l’approche MST. L'importance d'utiliser plusieurs marqueurs a été soulignée à plusieurs reprises dans la littérature et une approche pragmatique et pratique a semblé être l'adoption d'une « boîte à outils » ou MST « toolbox » constituées de différents marqueurs de suivi des sources. Cette thèse a été consacrée en premier lieu à l’application et la validation de boîtes à outils opérationnelle composées de marqueurs chimiques et moléculaires permettant de tracer les contaminations fécales d’origine humaine (eaux usées) et ce en différentes matrices environnementales et dans différentes conditions hydrométéorologiques et en deuxième lieu au suivi du devenir et du comportement des marqueurs dans le milieu naturel.» et «----------ABSTRACT: Effective management of fecal contamination episodes in aquatic systems requires first identifying the sources of contamination before being able to put in place management practices to restore the quality of a system. Fecal indicator bacteria (E. coli, fecal coliforms) are used for monitoring water quality; however, they indicate the presence of a recent fecal load and do not allow a differentiation of the origin of the fecal pollution. A lot of work has been done in recent years to develop a new approach, named Microbial Source Tracking (MST). Microbial source tracking techniques are intended to allow practitioners and researchers to identify the source(s) of fecal pollution in waters. Several studies have identified microbiological and chemical markers that can discriminate among sources; however, there are no defined "standard" methods for the MST approach. The importance of using several markers has been repeatedly emphasized in the literature and a pragmatic and practical approach is the adoption of a "toolbox" or MST "toolbox" consisting of different source tracking markers. This thesis was devoted firstly to the application and validation of operational toolboxes composed of chemical and molecular markers allowing to track human fecal contamination (wastewater) in different environmental matrices and in different hydrometeorological conditions and secondly to the monitoring of the fate and behavior of markers in the natural environment. To do this, 3 main objectives have been targeted. The first objective is in line with the action plan aimed at the research and elimination/correction of illicit connections in several municipalities in Quebec as required by the Ministry of municipal affairs, regions and land occupancy.

Automated Targeted Sampling of Waterborne Pathogens and Microbial Source Tracking Markers Using Near-Real Time Monitoring of Microbiological Water Quality

Waterborne pathogens are heterogeneously distributed across various spatiotemporal scales in water resources, and representative sampling is therefore crucial for accurate risk assessment. Since regulatory monitoring of microbiological water quality is usually conducted at fixed time intervals, it can miss short-term fecal contamination episodes and underestimate underlying microbial risks. In the present paper, we developed a new automated sampling methodology based on near real-time measurement of a biochemical indicator of fecal pollution. Online monitoring of β-D-glucuronidase (GLUC) activity was used to trigger an automated sampler during fecal contamination events in a drinking water supply and at an urban beach. Significant increases in protozoan parasites, microbial source tracking markers and E. coli were measured during short-term (<24 h) fecal pollution episodes, emphasizing the intermittent nature of their occurrence in water. Synchronous triggering of the automated sampler with online GLUC activity measurements further revealed a tight association between the biochemical indicator and culturable E. coli. The proposed event sampling methodology is versatile and in addition to the two triggering modes validated here, others can be designed based on specific needs and local settings. In support to regulatory monitoring schemes, it should ultimately help gathering crucial data on waterborne pathogens more efficiently during episodic fecal pollution events

Demonstrating the reduction of enteric viruses by drinking water treatment during snowmelt episodes in urban areas

This study investigates short-term fluctuations in virus concentrations in source water and their removal by full-scale drinking water treatment processes under different source water conditions. Transient peaks in raw water faecal contamination were identified using in situ online β-D-glucuronidase activity monitoring at two urban drinking water treatment plants. During these peaks, sequential grab samples were collected at the source and throughout the treatment train to evaluate concentrations of rotavirus, adenovirus, norovirus, enterovirus, JC virus, reovirus, astrovirus and sapovirus by reverse transcription and real-time quantitative PCR. Virus infectivity was assessed through viral culture by measurement of cytopathic effect and integrated cell culture qPCR. Virus concentrations increased by approximately 0.5-log during two snowmelt/rainfall episodes and approximately 1.0-log following a planned wastewater discharge upstream of the drinking water intake and during a β-D-glucuronidase activity peak in dry weather conditions. Increases in the removal of adenovirus and rotavirus by coagulation/flocculation processes were observed during peak virus concentrations in source water, suggesting that these processes do not operate under steady-state conditions but dynamic conditions in response to source water conditions. Rotavirus and enterovirus detected in raw and treated water samples were predominantly negative in viral culture. At one site, infectious adenoviruses were detected in raw water and water treated by a combination of ballasted clarification, ozonation, GAC filtration, and UV disinfection operated at a dose of 40 mJ cm−2. The proposed sampling strategy can inform the understanding of the dynamics associated with virus concentrations at drinking water treatment plants susceptible to de facto wastewater reuse.</p

Fecal contamination of storm sewers: Evaluating wastewater micropollutants, human-specific Bacteroides 16S rRNA, and mitochondrial DNA genetic markers as alternative indicators of sewer cross connections

International audienceA set of fecal indicator bacteria and alternative markers were tested for their use to identify priority sectors of two urban watersheds in the Greater Montreal region with unintended household sewage connections to storm drainage systems. Analyses were performed for thermotolerant (fecal) coliforms (FC), Escherichia coli, human-specific Bacteroidales (HF183) and mitochondrial DNA (Hmt) markers, carbamazepine (CBZ), caffeine (CAF), theophylline (THEO) and acetaminophen (ACE). A high incidence of human fecal contamination was observed, illustrating the need for a method to appropriately prioritize sectors for the rehabilitation of sewer cross-connections. Concentrations of alternative markers were not significantly different between the residential and industrial/commercial/institutional (ICI) sectors. However, median E. coli concentrations were higher in the residential as compared to ICI sectors (p  0.61, p  0.59, p < 0.05), possibly as a result of higher E. coli inputs from other sources such as domestic animals or fauna in the residential sector. Thresholds were determined to relate alternative markers to E. coli for use in an index for prioritizing sectors with sewer cross-connections. HF183, Hmt, CAF, THEO, and ACE were identified as suitable markers for identifying sewer cross-connections and are more reliable than E. coli alone, most importantly in residential sectors